Jul 16, 2019
A coolant absorbs heat from the mold during the injection molding process. The transfer of the absorbed heat from one coolant to another heat transfer medium (like air, water, …) is done by a machine named heat exchanger.
Simplified, a heat exchanger allows the transfer of thermal energy from one heat transfer medium to another.
Heat exchangers are used whenever the needed temperature of a process is above the ambient temperature.
Default temperatures for injection molding are in between 30 °C to 80 °C.
Two basic types of heat exchangers can be distinguished:
1. Water-Air:
The absorbed energy will be released to the ambient air.
2. Water-Water:
The absorbed energy will be released to a secondary water circuit.
Temperature Control: Heat exchanger within a
compression chiller
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Nov 15, 2018
In the mold, the correct temperature transfer between different materials is of crucial importance. The heat transfer inside the mold depends on a material depended-value, the heat transfer coefficient. The higher it is, the better is the transfer of the thermal energy from one material into the next one. As the hot runner system should transfer as little heat as possible to the remaining mold, an air gap helps to receive a small heat transfer coefficient, to get an isolated system.
It is necessary to know, that the heat transfer coefficient is no a constant value. It depends on material specific properties, like specific heat capacity, density and thermal conductivity, as well as geometry and roughness of the surface and for moving fluids on the flow behavior.
Nov 5, 2018
In hot runner systems heater bands are used. This is to bring the temperature inside of the melt channel up to the wanted process temperature and keep it constantly at this level.
The hot runner system consists mostly of one manifold and one or more hot runner drops.
In order to control the temperature a sensors are used in combination with PID-Controller.
The aim is to reach a homogeneous temperature distribution within the melt channel.
Nov 4, 2021
If it is necessary to determine the height of a molded part for a base plate, a height gauge is used for this purpose.
In addition to height measurement, the device can also be used for marking parts to be machined.
In this case, the pointer is sharpened and serves as a scriber.
The measurement determined or set in each case is usually shown on an LCD display.
It should be noted that the height measuring device is placed on a clean and level plate.
Measuring technology: Height Gauge on a metal plate for determining the height of a plastic
part.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Feb 23, 2023
Friedrich Wilhelm Herschel was born in Hannover (Germany) in 1738 and died in Slough (England) in 1822.
Since 1770 he was engaged in building astronomical instruments and in 1781 he discovered the planet Uranus in our solar system.
In the course of time he created a catalog with more than 2500 entries of nebulous objects and double stars.
In search of materials with better optical properties, he discovered infrared radiation in 1800 by directing sunlight through a prism
and using a thermometer to detect a further rise in temperature behind the red end of the visible spectrum.
He concluded that some invisible form of energy must be operating there.
Today, we use infrared cameras to record the thermal radiation of plastic parts, for example, and use it to evaluate the quality of the manufactured parts.
Bust of Wilhelm
Herschel
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
